The only places that should give you trouble are the far east empire and the southern desert. The warriors of the far east capital have a one-hit ko special, and the southern desert has tough troups with a fast hit rate (it also has the toughest random encounters). The 'elite snipers' from the desert capital are the best ranging units, the black ninjas from the east are the best close colmbat units (they cost 100k each). Very enjoyable game. The best con-based armor is the infernal helmet and plate from the holy cross's capital annd the holy shield from the forest's capital.
All of the effect are useless, its best simply to grow as your opponent grows, but since it's a stupid AI it'll eventually split, letting you eat it and win.
Favorite game on Kongregate. Can't find anything wrong with it. Lost track of the number of times I've finished it. I don't know why a lot of people are complaining about lag, my $750 3 year old computer can handle this fine.